Project: Synergistic Effects of Iron, Carbon Dioxide and Temperature on the Fate of Nitrate: Implications for Future Changes in Export Production in the Southern Ocean

Description from NSF award abstract:
This award provides support for "Collaborative Research: Synergistic Effects of Iron, Carbon Dioxide, and Temperature on the Fate of Nitrate: Implications for Future Changes in Export Production in the Southern Ocean" from the Antarctic Organisms and Ecosystems program in the Office of Polar Programs at NSF. The project will use a novel combination of research approaches to evaluate the effects of temperature, carbon dioxide, and iron on three ecologically- and biogeochemically-critical Southern Ocean phytoplankton functional groups: Large centric diatoms, small pennate diatoms, and Phaeocystis antarctica.

The Southern Ocean around Antarctic is undergoing several changes including increased temperature and carbon dioxide content, as well as changing levels of biologically available iron. The project goals are to understand how the individual and combined influences of these three variables affect Southern Ocean phytoplankton community structure, and to determine how these assemblage-level responses are linked to fundamental cellular responses at the levels of nutrient physiology and gene expression. The research team will focus on three different types of marine algae: large and small diatoms, and the prymnesiophyte, Phaeocystis antarctica. Shifts between these three major algal groups have very different consequences for nutrient and carbon biogeochemistry in the rapidly changing Antarctic marine environments. However, the mechanistic underpinnings of these environmentally-driven community shifts are not known. The project includes a US-based laboratory component with Antarctic isolates, field study at McMurdo Station, and then a cruise of opportunity in the upwelling areas directly south of the Antarctic Circumpolar Current. The study also includes collection and analysis of environmental gene expression data, or meta-transcriptomics, both from the field and experimental settings. The transcriptomes will be generated under environmentally relevant conditions and will thus contain information critical for decoding the genomes of several newly sequenced polar phytoplankton species in addition to the three groups highlighted above.

Related publications:
Bertrand, E.M., McCrow, J.P., Moustafa, A., Zheng, H., McQuaid, J., Delmont, T., Post, A.F., Sipler, R., Spackeen, J.L., Xu, K., Bronk, D.A., Hutchins, D.A., Allen, A.E. 2015. Phytoplankton-bacterial interactions mediate micronutrient colimitation at the coastal Antarctic sea ice edge. Proceedings of the National Academy of Sciences. 10.1073/pnas.1501615112